Japan's nuclear crisis: Fukushima plant stability in sight?

The crippled reactors at Japan's Fukushima Daiichi nuclear power plant are stable more than four months after the devastating earthquake and subsequent tsunami rocked the north, says the plant's operator.

The installation work of a roof at unit 3 turbine building at the tsunami-crippled Fukushima Daiichi Nuclear Power Station in Fukushima prefecture is seen in this July 18 handout photo. Japan's government said on Tuesday it was on track with efforts to take control of the crippled Fukushima nuclear plant but cautioned that a final clean-up of the worst nuclear accident since Chernobyl would take many years.

The crippled reactors, three of which went into partial meltdowns, are stable more than four months after the devastating earthquake and subsequent tsunami rocked the north, says the government and plant operator. Now the reactors appear to be on track for a cold shutdown.

Reactor No. 3

Days after Japan's government announced it would conduct "stress tests" at all of the country's atomic facilities, the plant's operator, Tokyo Electric Power (Tepco), said it would start injecting nitrogen into the No. 3 reactor – one of three that suffered meltdowns in the aftermath of the March 11 earthquake and tsunami.

That unit was the only one of the three stricken reactors that hadn't received injections of the inert gas, which lowers hydrogen levels inside the units and prevents the kind of explosions that rocked the facility four months ago.

Tepco had said that treating the reactors with nitrogen was critical to its broader aim of stabilizing them by mid-July. But the injections carry the risk of causing further radiation leaks from the reactor's containment vessel. Japan's nuclear safety agency said any leaks would not be big enough to hurt the surrounding environment.